Increasing crop yields is probably the single most important objective of any agricultural production program. Several methods are known for increasing crop yield, including the use of fertilizers and pesticides. These methods are limited by the plant's inherent inefficiency in utilizing atmospheric carbon dioxide (CO.sub.2) in the biological process known as photosynthesis. In photosynthesis, plants utilize sunlight, carbon dioxide, and water to synthesize carbohydrates such as starch, sugars and celluloses. When water is removed from plants, 90-95 percent (%) of the dry matter remaining is derived from the atmospheric CO.sub.2 fixed during photosynthesis. Since crop yield is dependent upon the efficiency of this process, by increasing the efficiency of photosynthesis, crop yield can be similarly increased. At the same time photosynthesis is occurring, another plant process counter-productive to photosynthesis is also operating--photorespiration. Photorespiration, which occurs simultaneously with photosynthesis in plant tissues, is the light-dependent carbon oxidation process by which oxygen (O.sub.2) is taken up and CO.sub.2 released. Photoerspiration reduces the net CO.sub.2 fixing capacity operating in photosynthesis by 20-50 percent (%). Therefore, net photosynthesis (and the subsequent crop yield) can be increased directly by reducing the amount of CO.sub.2 lost during photorespiration--a process which has no known function in plant life.
Inhibiting photorespiration will therefore increase net photosynthesis. The present invention has the advantage of providing compounds, compositions and methods for enhancing photosynthesis by inhibiting the first enzyme (glycolate oxidase) of the wasteful photorespiratory pathway. It is believed that inhibiting glycolate oxidase will close down or at least retard photorespiration and thus conserve the carbon which would otherwise be lost as CO.sub.2 into the atmosphere. With more carbon available to the plant, the rate of photosynthesis is enhanced, ultimately leading to an increase in crop yield.